Seminary student Michael Kovak (Colin O'Donoghue) reluctantly attends exorcism school at the Vatican. While he’s in Rome, Michael meets an unorthodox priest, Father Lucas (Anthony Hopkins), who introduces him to the darker side of his faith, uncovering the devil’s reach even to one of the holiest places on Earth.

Michael Kovak, disillusioned with his father, a mortuary owner, decides to enter a seminary school and abdicate his vows upon completion, thereby getting him a free college degree. Four years pass and Michael is being ordained to the diaconate at the seminary. However, after ordination he writes a letter of resignation to his superior, Father Matthew, citing a lack of faith.
While Father Matthew is attempting to catch Michael, he trips, causing a biker to swerve into the path of an oncoming car. The young woman, believing Michael to be a priest after seeing his clerical garb, asks him for absolution. Unable to refuse, Michael comforts her and performs the ritual absolving her sins. Seeing how calmly he handled the situation, Father Superior tells Michael he is called to be a priest, whether Michael believes this or not; he later approaches Michael with an invitation to travel to Rome in order to attend a class on exorcism. Michael reluctantly accepts after being told by Father Matthew that he will be levied a $100,000 student loan if he leaves immediately, but that if he still desires to resign from his position after taking the class, then he may be free to leave.